Petroleum gases, ethane, propane, butane and isobutane and their unsaturated analogs, ethylene, propylene, butene and isobutene, are produced during cracking of petroleum feeds. Those petroleum gases, sometimes referred as LPG, may be sold, as is. Alternatively, portion of the gases, e.g., propylene, butenes and isobutane can be converted into alkylate, which have a desirable antiknock rating. Moreover, the petroleum gas can be subjected to oligomerization to produce C.sub.5 -C.sub.10 paraffins and to dehydrocyclization to produce aromatics. High yields of LPG during catalytic cracking contribute to low product value for an operating refinery. Both the charge stock and severity of operating conditions can influence LPG production. Although refineries can utilize at least a portion of the butane for gasoline blends, the propane and any remainder butane, if sold, will be sold at a large discount (currently about $20/bbl) compared to gasoline or alkylates (currently about $35/bbl). It is, therefore, highly desirable to upgrade the normal saturated LPG produced during cracking.